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Midnight density maximum in the thermosphere from the CHAMP observations
Author(s) -
Ruan Haibing,
Lei Jiuhou,
Dou Xiankang,
Wan Weixing,
Liu Yong C.M.
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2013ja019566
Subject(s) - thermosphere , midnight , atmospheric sciences , middle latitudes , latitude , solar maximum , solar minimum , satellite , ionosphere , environmental science , climatology , physics , solar cycle , geology , astronomy , solar wind , plasma , quantum mechanics
The midnight temperature maximum (MTM) is generally believed to occur over the equatorial region, while a few recent studies suggested the extension of the MTM to middle and high latitudes. In this paper, we investigate the latitudinal variations of nighttime thermospheric density on the basis of the accelerometer measurement onboard the CHAMP satellite during 2002–2009. The sampling of the CHAMP satellite allows for observation of a statistical average of the midnight density maximum (MDM). From these observations, it was found that the MDM of the thermosphere, a manifestation of the MTM, occurs in all seasons at both low and high solar activities, but its features vary significantly with season and solar activity. The peak of the MDM over the equatorial region occurs at ~01:00 LT under the low solar activity condition, whereas it happens about 1–2 h earlier at high solar activity. We observe extension of the MDM from the equatorial region to southern midlatitudes, especially under the low solar activity condition.